Do you mean like a lens flare? If so allow me to suggest Knoll's plug-in. It is amazing. You can even have your cloud layer (or text or whatever) block out the light when it goes across it. Very useful.
If you just want the beams of light there's always Trapcode's Shine. There's an example of sunbeams on that page.
Alternatively (and more difficultly) some sort of radial blur color-corrected and set to add or screen.
- The Great Szalam
(The 'Great' stands for 'Not So Great, in fact, Extremely Humble')
No trees were harmed in the creation of this message, but several thousand electrons were mildly inconvenienced.
Thanks for the tippers. I simply had a little 3d country scene with a street, trees, houses, clouds, mountains and was just looking for something that might capture the beauty of a sunrise allow me to show some bursting rays of sunlight appear off the horizon and then through the trees to be more and cast its glory on to this seen.
I tried shine but didn't seem to do what I wanted. Maybe settings were so great. I'll play a little more. thanks..